A Thin Film Transistor Liquid Crystal Display (TFT-LCD) comprises an array substrate, a color filter substrate and a liquid crystal layer disposed between the array substrate and the color filter substrate. In the color filter substrate, pixel regions comprising color resins of three colors of red, green and blue and non-pixel regions comprising black matrices formed at gaps between the color resins of the three colors of red, green and blue are formed on the color filter substrate, and common electrodes are formed on the black matrices (non-pixel regions) and the color resins (pixel regions).
FIGS. 1 and 2 show a LCD panel fabricated by cell-assembling the color filter substrate and the array substrate. In the LCD panel, the array substrate comprises: a first transparent substrate 101, a light-shielding strip 104, a data line 102, a gate line (not shown in the figure) and a pixel electrode 103 formed on the first transparent substrate 101; the color filter substrate comprises: a second transparent substrate 201, a color resin 202, a black matrix 203 disposed at gaps between color resins and a common electrode 204 overlaying the color resin and the black matrix. Moreover, the liquid crystal layer comprising liquid crystal molecules 30 is disposed between the color filter substrate and the array substrate.
With reference to FIG. 2, in the non-pixel region of the LCD panel, there is a complicated electric field consisted of electric fields generated between the common electrode 204 on the color filter substrate and the edge of the pixel electrode 103 on the array substrate, between the common electrode 204 on the color filter substrate and the data line 102 on the array substrate, between the edge of the pixel electrode 103 on the array substrate and the data line 102 on the array substrate, between the common electrode 204 on the color filter substrate and the light-shielding strip 104 on the color filter substrate, which makes the orientation of the liquid crystal molecules 30 in the non-pixel region abnormal. Due to the presence of the black matrix 203, the black matrix can block the transmittance of the light even if the liquid crystal molecules 30 are of abnormal orientations. However, when the color filter substrate and the array substrate are misaligned, the abnormally-oriented liquid crystal molecules 30 in the non-pixel region cause different light transmittance, as a result, the first black matrix 203a parallel to the data line 102 can not block the light from the abnormally-oriented liquid crystal molecules in the non-pixel region, which may lead to pixel light leakage and reduce the picture quality of the display device.